DESCRIPTION (Investigator's Abstract): Lipid peroxidation (LP) is an ubiquitous biochemical process involving the reaction of oxygen or oxygen-derived radicals with polyunsaturated lipids resulting in the generation of a variety of peroxidized lipids. Elevated levels of certain LP products have been associated with a variety of human diseases including cataract formation, senile dementia and cardiac ischemia along with the aging process. In this study initially a normal human population constituting various aged individuals will be studied in order to ascertain the normal values for LP parameters and antioxidant levels. The serum LP parameters measured will include malondialdehyde levels determined by HPLC, lipid hydroperoxides determined by chemiluminescence, and water-soluble fluorescent substances. Antioxidant levels measured will include Vitamins A, E and C. Each of these parameters will be correlated with age to determine if there is a trend towards an increased level of LP with age. Since the concentration of polyunsaturated fatty acids (PUFA) in membranes is related to the susceptibility of an organism to LP, 72 hour dietary recall data will be collected from each participant in order to determine the relative level of daily PUFA intake. This is important in light of the emphasis on increased dietary intake of PUFA as a means of reducing serum cholesterol levels. These individuals may have an increased susceptibility to LP. In the final stage of this project, plasma and dietary information will be collected from patients with diagnosed diseases believed to be related to LP. Plasma will be collected and analyzed for LP parameters and antioxidant levels as described above and compared to the normal values previously obtained. The results of these studies will provide a database of the normal levels of LP products. In addition, these studies should provide the information required to determine if a correlation exists between LP and age, or between LP and specific disease states. If a correlation can be demonstrated between LP and the aging process or specific disease states more mechanistic cause/effect studies can be designed in the future.